We were just talking about this today. @eviltrout has it on his plate to only show pinned category definition topics for the current category (no subcategories). In other words at most one of these definition topics showing for whatever category you are viewing.

Currently discourse only hides description pins from sub-categories. Would it be possible to extend this to all sub-category pins, or somehow allow other pins in sub-categories to be hidden in parent categories?

On our forum some categories have both a description pin, and also a number of “template” topics pinned. Having all of these templates appear in the parent category quickly makes it look messy.